Presently, the machine type communication (MTC) technology is gradually developed. It can be expected that in the near future, the number of MTC devices will be continuously increased and will eventually exceed the number of human-to-human communication (H2H) devices. In an existing wireless communication system, H2H devices and MTC devices are allowed to access the same random access resources. If there are a large number of MTC devices, the random access channels (RACH) may be overloaded, and accordingly the H2H devices cannot carry out communication procedures properly. In order to avoid such situation, the base station may configure large amount of RACHs for MTC devices and H2H devices performing random access procedure. As a result, the increasing RACH resource will reduce the available wireless communication resources to other wireless communication functions.
To prevent affecting the normal wireless communication functions, two conventional resolution approaches have been proposed, and it avoids RACH overload when a large number of MTC devices carrying out wireless communication procedures. The first resolution approach is MTC devices oriented (which may be referred to as a push based technique). The first resolution approach can be further categorized into: (a) application level time separation, where MTC devices in different groups are arranged to access wireless network at different times; (b) specific back-off (BO) scheme, where when a collision is encountered, MTC devices adopt different BO times to reduce the possibility of another collision; (c) specific access class barring scheme (or specific ACB scheme), where MTC devices are grouped in advance to use different ACB factors, and MTC devices corresponding to different ACB factors use different ACB timers, so as to control the admission of random access to reduce the collision possibility; (d) separate RACH resource, wherein MTC devices and H2H devices use different RACHs for their random access process.
The second solution approach is a pull based technique, where the MTC devices passively receive RA time points appointed by a network.
Although the push based resolution approach is proposed, the existing parameter assignment methods of wireless communication systems are not able to support the approach for MTC devices. For example, the BO parameter assignment method in an existing wireless communication system cannot accomplish the specific BO schemes mentioned above. It is because that when different wireless communication devices attempt to transmit preamble codes to a base station at the same time, the base station cannot distinguish H2H devices and MTC devices and still assign the same BO parameter to these communication devices. For example, in an existing wireless communication system, both ACB parameters and RACH parameters are delivered by the base station (for example, an eNB broadcasts these two types of parameters in its system information blocks (SIB)). These parameters are broadcasted and have periodic appearance periods, and accordingly, a longer modification period has to be specified to prohibit making the adjustments of these ACB parameters and RACH parameters during the period. For example, an ACB parameter or a RACH parameter can only be modified once at the modification period boundary (MPB) of SIB2, which cannot immediately change system information based on the loading of RACH. Thus, an existing wireless communication system cannot effectively respond to the loading of a RACH, and H2H devices which do not need aforementioned parameters still have to receive such system messages.
Thereby, it is a major concern in the industry to prevent MTC devices from affecting H2H devices when the MTC devices perform random access procedures and effectively reflect the utilization state (network loading state) of a RACH, so as to adjust the RA behaviors of the MTC devices in real time.